Tape cartridge having lockout rails

ABSTRACT

A tape cartridge has a front face sized for compatibility with an industry standard tape drive, and has sides longer than the sides of some industry standard cartridges. The sides and top of the housing extend outwardly in width to form a back portion of the cartridge that is wider than the front portion and prevent the cartridge from being inserted into non-compatible tape drives. Two large diameter tape hubs improve the empty hub to full pack diameter ratios, and improve the resulting tangential drive force and tape tension profiles as the tape moves between the hubs. Flanges are permanently bonded to the hubs to prevent the tape packs from shifting and a spring biases the hubs against the baseplate. A back set of rollers includes a high-drag roller that engages the drive belt at a fixed wrap angle and produces a relatively constant drag. A front set of rollers includes a drive roller and has rollers mounted to form substantially equal geometries with rollers in the back set respective to the tape hubs. The constant wrap angle of the high-drag roller tends to outweigh varying drags from other rollers, causing less change in tape tension and tangential drive force as the tape is transferred from hub to hub. A door covers the capstan and media access openings in the front face of the cartridge when the cartridge is outside of a tape drive. A write protect arm is pivotally mounted at the front face of the cartridge.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.09/288,069, filed Apr. 7, 1999, U.S. Pat. No. 6,068,207, which is adivision of U.S. application Ser. No. 09/135,017, filed Aug. 14, 1998,U.S. Pat. No. 6,045,079.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention pertains in general to tape cartridges adapted for themagnetic recording of information and in particular to an improvedcartridge having increased tape capacity and higher performance.

2. Description of the Related Art

For many years, magnetic recording tape has been utilized as aninexpensive and reliable medium for the storage and retrieval of dataprocessing information. In the personal computer industry, it has becomethe practice to use tape cartridges to hold the tape and facilitate easyloading of the magnetic tape into a suitably adapted tape drive.Moreover, cartridges protect the magnetic recording tape fromcontamination and inadvertent contact during operation within the tapedrive, as well as during storage outside of the tape drive. Wideacceptance of tape cartridges promoted adoption of standardconfigurations by the data processing industry.

As the data processing industry advances, there is a need forlarger-capacity, belt-driven tape cartridges. Such larger tapecartridges may have a cartridge-drive interface compatible withcommercially available industry standard tape drives. If the cartridgeis not compatible with industry standard tape drives, the cartridgeshould have a mechanism to prevent the cartridge from being insertedinto an incompatible tape drive.

One way to increase the capacity of a tape cartridge is to increase thelength of tape stored therein. Since the volume within a tape cartridgeis limited, some cartridge designs increase tape length by decreasingthe thickness of the tape. Other designs increase available volume byextending the length of the cartridge while maintaining an industrystandard cartridge-drive interface (see, for example, U.S. Pat. No.4,262,860).

However, lengthening the tape exacerbates undesirable characteristics inthe cartridge design. For example, tape tension is attributable to thedifference in belt tensions applied to the two tape packs. This is afunction of the diameters of the two packs and changes as tape movesfrom one pack to the other. A bow-tie tension profile of tape movingwithin a conventional belt-driven tape cartridge indicates the change intape tension over the entire length of tape as it moves from hub to hubwithin the cartridge. The bow-tie profile is partly determined by theratio of the diameter of an empty hub to the diameter of a full tapepack on a hub. Since a longer tape results in an increased tape packdiameter, a longer tape worsens the bow-tie profile of tape tension fora given design of tape cartridge.

Similarly, the tangential drive force (“TDF”) is the amount of forceneeded to drive the tape within a cartridge in either direction. TDF isdetermined by the total drag of all components in the cartridge and ispreferably constant regardless of the amount of tape on each pack. Thedrags produced by certain components, like the rollers guiding the drivebelt, however, vary as a function of the tape pack diameter. As with thebow-tie tension profile, therefore, a longer tape results in a greatervariation in TDF as the tape moves from pack to pack. These variationsin the bow-tie tension and TDF profiles may detract from the performanceof the tape cartridge.

In addition, the tape in the tape packs tends to vertically shift whenthe tape cartridge is subject to stress. To limit the extent of thisshift, some tape cartridges have flanges attached to the top and bottomof each hub. However, these flanges cannot withstand high levels ofstress and are not adequate for large tape packs.

Industry standard tape cartridges, moreover, have a door pivotallymounted at the front of the cartridge to protect the tape media passingthrough an opening in the front face of the cartridge housing when thecartridge is outside of a tape drive. The door is typically biasedclosed when the cartridge is outside the drive, and cammed open by arail in the tape drive when the cartridge is inserted therein. The door,however, does not cover a second opening in the front face through whichthe drive roller and portion of the tape are exposed, and which allowsdust and other contaminates to contact the media.

Industry standard tape cartridges additionally have a write protect locklocated near the front left comer of the cartridge. This lock istypically a sliding or rotating two-position switch and is oftendifficult to manipulate.

Accordingly, there is a need for an increased capacity cartridge havinga mechanism for preventing insertion into a non-compatible drive anddecreased variation in tape tension and TDF commonly associated withcartridges having increased tape length. In addition, the cartridgeshould have improved hubs to support the larger tape packs, a door thatmore efficiently protects the media from contamination, and a writeprotect lock that is easier to manipulate.

SUMMARY OF THE INVENTION

In accordance with the present invention, a tape cartridge preferablyhas a longer housing than industry standard tape cartridges. Thecartridge housing has a planar front face having media and capstanaccess openings compatible with an industry standard tape drive.Preferably, the top and sides of the cartridge include transitionalsegments positioned rearwardly of the front face which extend laterallyoutward from the center to make the rear portion of the cartridge widerthan the front portion. These transitional segments encounter componentsof a conventional tape drive that is equipped to receive conventionaltape cartridges, and prevent the tape cartridge of the present inventionfrom being fully inserted into such a non-compatible tape drive.

Two tape hubs are rotatably mounted on a baseplate at respective firstand second axes of rotation perpendicular to the plane of the front faceand slightly askew of a center line extending from the front face of thecartridge to the back of the cartridge. In order to reduce the variationin bow-tie and TDF tension profiles introduced by a long length of tape,the hubs preferably have a larger diameter than the diameter of hubstypically found in other industry-standard tape cartridges. Thus, theratio of hub size (i.e. empty tape pack) to full tape pack size isreduced, contributing to decreased variations in the bow-tie tensionprofile. Moreover, each hub preferably has an integrally molded bottomflange and a ultrasonically welded top flange for preventing the tapepacks from shifting. In a preferred embodiment, a spring is positionedbetween the hubs and the housing to bias the hubs toward the baseplate,thereby stabilizing the position of the hubs with respect to thebaseplate.

First and second sets of rollers are rotatably mounted on the baseplatein the same plane as the tape hubs and serve to guide a drive beltthrough the cartridge. Each tape hub has an associated set of threerollers. Two rollers of each of the first and second roller sets aremounted substantially symmetrically with the respective first and secondrotational axes of the tape hubs. This arrangement keeps the belt lengthalmost constant regardless of tape pack size, resulting in an almostconstant static installed belt tension and a more constant componentdrag over the full range of tape packs on each hub. A roller in thefirst set of rollers is the drive roller and has a flange that protrudesthrough the capstan access in the front face of the cartridge forengaging a capstan of a tape drive when the cartridge is insertedtherein. The capstan imparts rotational movement to the drive roller andthe associated drive belt which, in turn, rotates the tape packs andmoves the tape from pack to pack within the cartridge.

The belt rollers preferably have a constant low level of rotationaldrag. However, several of the rollers engage segments of the drive beltthat are also wrapped around a tape pack. Since the sizes of the tapepacks vary as the tape moves through the cartridge, the wrap angles ofthe belt relative to the low-drag rollers vary. Therefore, the sideloads exerted by the belt also vary depending upon tape pack size. Sinceside load affects the amount of drag produced by a roller, the combineddrags of the relatively low-drag rollers vary as a function of tape packsize.

In accordance with one embodiment of the present invention, a high-dragroller associated with the second tape pack is positioned between twolow-drag belt rollers and engages the drive belt at a constant wrapangle. Accordingly, the side load exerted by the belt on the high-dragroller is constant and, therefore, the drag produced by the roller issubstantially constant. Since the varying drags introduced by thelow-drag belt rollers are outweighed by the constant drag introduced bythe high-drag roller, the cartridge tends to have a more constantbow-tie tension profile and resulting TDF.

A door is pivotally mounted near the front right corner of the tapecartridge and biased to cover the media and capstan access openings inthe front face of the cartridge when the cartridge is outside of thetape drive. In addition, a write protect lock comprising a pivotallymounted arm is positioned near the left front corner of the tapecartridge to selectively engage a sensor switch within a compatible tapedrive when the tape cartridge is fully inserted therein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a tape cartridge of one embodimentillustrating the length and varying width of the baseplate and thecomponents therein;

FIGS. 2A, 2B, and 2C are, respectively, bottom, top, and side views ofthe tape cartridge embodiment of FIG. 1 including the housing;

FIG. 3 is a perspective view of a tape cartridge of another embodimentillustrating the length and width of the baseplate and the componentstherein; and

FIGS. 4A, 4B, and 4C are, respectively, bottom, top, and side views ofthe tape cartridge embodiment of FIG. 3 including the housing.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a perspective view of a tape cartridge 100 according to oneembodiment of the present invention. As used herein with respect to thefigures, terms like “width” or “wider” refer to the dimensions of thecartridge in the direction of arrows W and W′, while “length” or“longer” refer to the dimensions in the direction of the arrows L. The“front” or “front face” of the cartridge is the side of the cartridgehaving the cartridge-drive interface, while the “back” of the cartridgeis the side opposite the front. The “base” or “bottom” of the cartridgeis the side which typically is the lower side of the cartridge wheninserted into a drive, while the “top” is the side opposite the base orbottom. The “left” and “right” sides of the cartridge are as definedlooking from the back toward the front of the cartridge with the topside up. It should be understood that use of these terms is for clarityonly, and the cartridge may function in any orientation.

The tape cartridge 100 of FIG. 1 is surrounded by a substantially rigidcover or housing (not shown in FIG. 1) that is mounted on the baseplate103 along with other components of the cartridge, as described laterherein. The front 102 of the cartridge preferably has a width of about3.18 inches and is dimensioned and has cartridge-drive interfaceopenings in accordance with the American National Standards Institute(ANSI) specification X.3.249-1995 [Unrecorded Tape Mini-Cartridge ForInformation Interchange, 0.25 in (6.30 mm), 10,000-14,700 ftpi (394-579ftprmm) coercivity 550 oersteds (44,000 amperes/meter)]. The back 104and rear portion of the baseplate 103, in contrast, is preferably about3.66 inches wide.

The left and right sides 106, 108 of the cartridge 100 extend from thefront 102 to the back 104 and are preferably about 6.9 inches in lengthand are flush with and perpendicular to the front face 102. Beginning ata point preferably approximately 0.7 inches from the front face 102, thesides 106, 108 extend laterally for approximately 1.0 inches in atapered or curved manner to a wider dimension W′ over the remaininglength to the rear portion of the back 104 of the cartridge 100. Thecartridge measurements stated herein are approximate and may vary due todifferent configurations of the cartridge housing and baseplate 103 forcompatibility with established industry standards. By having the back104 of the cartridge 100 wider than the front 102, and by extending thelength of the cartridge as illustrated in FIG. 1, additional volume iscreated within the housing for containing tape therein while maintainingan industry standard cartridge-drive interface at the front face 102.

Within the housing are front and back tape packs 110, 112, eachcomprising a rotatably mounted tape hub 114, 116 preferably locatedalong and slightly askew opposite sides of a defined center line 118extending lengthwise through the cartridge 100 and perpendicular to thefront face 102. The front hub 114 is mounted slightly to the left of thecenter line 118 and the back hub 116 is mounted slightly to the right ofthe center line 118. Each hub has a preferred diameter of about 1.1inches.

Upper and lower flanges 115, 117, 119, 121 (lower flange 121 is hiddenby the front tape pack 110) are preferably rigidly attached to each tapehub 114, 116 and are positioned to guide the tape 120 onto therespective hubs 114, 116. In one embodiment of the present invention,the lower flanges 119, 121 are integrally molded into the hubs 114, 116and the upper flanges 115, 117 are ultrasonically welded to the hubs114, 116. In another embodiment, the upper flanges 115, 117 areadhesively attached with a chemical bonding agent to the hubs 114, 116.Each flange has a preferred diameter of approximately 1.6 inches andprevents the tape 120 in the portions of the tape pack 110, 112 adjacentthe flange from vertically shifting. In one embodiment of the tapecartridge of FIG. 1, the ends of a leaf spring 174 are biased againstthe hubs 114, 116 and the center of the leaf spring 174 is flexedupwards to contact the underside of the top of the cartridge housing(not shown). The bias of the spring 174 provides downward force on eachhub 114, 116, which causes the hubs 114, 116 to contact the baseplate103.

The magnetic recording tape 120 passes from the front pack 110, oversets of pins 125, 127 (hidden behind the media access door 160), 130 andguides 126, 128, 132 to the back pack 112. One embodiment of the presentinvention has approximately 2000 feet of 8 millimeter-wide magneticrecording tape holding approximately 25 gigabytes of data, althoughvariations in the tape length and width may be used to produceembodiments holding different amounts of data. Pin 125 is positionedalong the tape path from the front pack 110 to the back pack 112 toprevent the tape 120 from encountering the left side of the cartridgehousing 106 when the front tape pack 110 is almost full. The tape alsoengages two guides 126, 128 which have upper and lower flanges forpositioning the height of the tape 120 relative to the base plate 103 asthe tape 120 passes through the access port 134 defined in the front 102of the cartridge through which a read/write head of a tape drive caninterface with the tape 120. The two guides 126, 128, in combinationwith another pin 127, define the plane of the tape 120 passing throughthe defined space of the access port 134 at a standardized heightrelative to the baseplate 103, and restrict the degree to which theread/write head may push the tape 120 out of the defined plane. Anotherpin 130 is positioned on the baseplate 103 to prevent the tape 120 fromencountering the drive belt 136, and a third guide 132 with upper andlower flanges positions the height of the tape 120 relative to thebaseplate 103 during tape movement to or from the back tape pack 112.

FIG. 1 illustrates the two conditions of the tape 120 when substantiallyfully wound about one of the hubs 114, 116. The figure illustrates thetape 120 by a solid line 122 when substantially all of the tape 120 iswound onto the front hub 114. Solid line 122 illustrates the front tapepack 110 at maximum diameter when the diameter of the back tape pack 112is minimum at substantially the diameter of hub 116. When substantiallyall of the tape 120 is transported to the back hub 116, the diameter ofthe front tape pack 110 is minimum and the diameter of the back tapepack 112 is maximum, as illustrated by broken line 124. In a preferredembodiment of the present invention, the minimum diameter of a tape packis approximately 1.1 inches, the maximum diameter of a tape pack isapproximately 3.2 inches, and the half-pack diameter, i.e., whenapproximately the same amount of tape is on both the front and back tapepacks 110, 112, is approximately 2.4 inches, although these latter twodiameters vary as a function of tape length and tape thickness.Accordingly, the ratio of maximum pack diameter to minimum pack diameteris approximately 3:1.

An elastic endless drive belt 136 constructed, for example, ofpolyurethane drives the tape packs 110, 112 in the manner as describedin the literature (see, for example, U.S. Pat. No. 3,692,255 entitledBELT DRIVEN TAPE CARTRIDGE, and issued on Sep. 19, 1972). The elasticityof the belt maintains the belt 136 in tension along a belt path incontact with a front set of rollers 142, 144, 146 and a back set ofrollers 148, 150, 152 and the outer wraps of tape on the tape packs 110,112. The front and back sets of rollers each comprise three rollers 142,144, 146 and 148, 150, 152 that are each rotatably mounted on axlesattached to the baseplate 103. Rollers 142, 144, 148, 150, and 152 havea preferred diameter of 0.43 inches. Thus, the diameters of the rollersare less than half the diameter of the hubs 114, 116.

The outer rollers 142, 146, 148, 152 within each of the front and backroller sets 138, 140 have substantially equal geometries with respect tothe front and back tape hubs 114, 116. Thus, the distance and anglebetween rollers 142 and 146, roller 142 and hub 114, and roller 146 andhub 114, are substantially equal to the distance and angle betweenrollers 152 and 148, roller 152 and hub 116, and roller 148 and hub 116,respectively. By orienting the tape hubs 114, 116 and sets of rollers138, 140 in this manner, the belt 136 length and associated elastictension remains substantially constant regardless of tape pack size,resulting in a substantially constant static installed belt tension andassociated substantially constant component drag. The length of the belt136 when substantially all of the tape is on the front hub 114 isapproximately 20.927 inches, when the tape is evenly distributed on thefront 114 and back hubs 116 is approximately 21.075 inches, and whensubstantially all of the tape is on the back hub 116 is approximately20.932 inches.

One factor of the tape tension equation is${K \cdot \left( {\frac{1}{P_{1}} - \frac{1}{P_{2}}} \right)},$

where K is the coefficient involving the physical constants of the belt,and P₁ and P₂ are the diameters of the two tape packs. According to thisequation, variations in tape tension result from the difference in thediameters of the tape packs and the characteristics of the belt. Since agreater diameter tape pack holds more tape around its circumference thana smaller diameter tape pack, the difference between minimum and maximumtape pack diameters is reduced by using a larger diameter hub. The hubs114, 116 according to a preferred embodiment of the present inventionhave larger diameters than industry-standard hubs and, therefore, thedifference between minimum and maximum tape pack 110, 112 diameters isreduced. Accordingly, the larger tape hubs 114, 116 and thesubstantially constant static installed belt tension result in a reducedvariation in tape tension bow tie profile as the tape moves through thecartridge 100.

Roller 146 within the front set of rollers 138 also serves as the driveroller and includes an upper flange having a diameter of about 0.486inches that is positioned to contact a capstan when the tape cartridge100 is inserted into a compatible tape drive having an industry-standardinterface. When so inserted, a read/write head enters the space of anaccess port 134 defined in the cartridge front 102 to make interfacecontact with the tape 120. At the same time, the flanged portion of thedrive roller 146 contacts the capstan. When the capstan rotates, therotation is imparted to the drive roller 146 and to the drive belt 136which is wrapped about a portion of the drive roller 146 below theflange having a narrowed diameter. The drive belt 136 engages the outerwraps of tape wound on the tape packs 110, 112 and causes the tape packs110, 112 to rotate. Depending upon the direction of rotation of thedrive roller 146, one tape pack serves as a supply pack and the otherpack serves as the take-up pack.

A media access door 160 is preferably pivotally mounted about a pin 162positioned adjacent to the right front comer of the cartridge 100 andpreferably extends from the right front comer of the cartridge 100 to apoint beyond the leftmost portion of the drive roller 146. The mediaaccess door 160 is biased closed by a spring wound around the pin 162.The closed media access door 160 covers a space defined in the frontface 102 through which the flanged portion of the drive roller 146protrudes, and the access port 134 defined in the cartridge front 102through which the read/write head of the tape drive engages the tape120. Accordingly, the closed media access door 160 covers and protectsthe exposed portions of the drive roller 146 and tape 120 fromcontamination while the cartridge 100 is outside a tape drive.

FIG. 1 illustrates a partial view of the left 170 and right 168 rails ofa tape drive for accepting the cartridge 100 embodiment illustrated inFIG. 1. When the cartridge 100 is inserted into the tape drive, anextended portion 172 on the right rail 168 of the tape drive engages theend 164 of the media access door 160 on the opposite side of the pivotpin 162 from the main body of the door and pivots the door open aboutthe pin 162, thereby allowing components of the tape drive to interfacewith the exposed components of the tape cartridge 100 when the tapecartridge is fully inserted in the tape drive.

A belt roller 142, 148 in each set of rollers 138, 140 is positionedbetween the tape hubs 114, 116 and is a “primary roller” positioned toshape the belt path away from the maximum diameter of the associatedtape pack. An intermediate roller 144 of the front set of rollers 138 ispreferably positioned adjacent to the front right comer of the tapecartridge 100 and the corresponding roller 150 of the back set ofrollers 140 is preferably positioned adjacent to the back left comer ofthe tape cartridge 100.

Rollers 142, 144, 146, 148, and 152 preferably exhibit the lowestpossible amount of rotational drag on the belt 136. In a perfect system,each of the rollers 142, 144, 146, 148, 152 would exhibit the sameamount of drag, or no drag at all. In fact, each roller inevitablyexhibits a slight difference in drag due to manufacturing tolerances. Inone embodiment, the amount of drag exerted by rollers 142, 144, 146,148, and 152 varies between approximately 0.01 and 0.11 oz/inches. Incontrast, roller 150 preferably exhibits a relatively high amount ofrotational drag relative to the other rollers 142, 144, 146, 148, 152for reasons described below. In one embodiment, roller 150 exertsapproximately 0.16 to 0.41 oz/inches of drag.

The drive belt 136 wraps about an arcuate portion of the front tape pack110 from a point adjacent to roller 146 to a point adjacent to roller148, and about an arcuate portion of the back tape pack 112 from a pointadjacent to roller 152 to a point adjacent to roller 142. Depending uponthe amount of tape 120 wound upon each of the tape packs 110, 112, theangles of wrap of the drive belt 136 on the tape packs 110, 112 relativeto the rollers 142, 146, 148, 152 defining the ends of the arcuateportions vary as tape moves between the tape packs 110, 112. Forexample, if substantially all of the tape 120 is wrapped upon the fronttape pack 110, the wrap angle of the belt 136 is approximately 154°about the front tape pack 110 and approximately 90° about the back tapepack 112. Furthermore, the wrap angle of the belt 136 is approximately189° about the drive roller 146 and approximately 79° about roller 142.In addition, the wrap angle of the belt 136 is approximately 134° aboutroller 148 and approximately 128° about roller 152. As the tape 120moves from the front tape pack 110 to the back tape pack 112, the wrapangles of the belt 136 about the tape packs 110, 112, rollers 146 and148, and rollers 142 and 152 inversely vary until the wrap angles abouteach pair of corresponding hubs and rollers are reversed. Regardless ofthe sizes of the tape packs, the wrap angles of the belt 136 aboutroller 144 remains approximately 63° and the wrap angle of the belt 136about roller 150 remains approximately 82°.

As the tape 120 moves through the cartridge 100 and the wrap anglesvary, the side loads, or forces that the drive belt exerts upon therollers 142, 146, 148 and 152, also vary. The side loads affect thebearing system of the rollers and cause the rotational drag of theserollers to increase as the side loads increase. Since total drag affectstape tension, the variations in drag can cause the tape tension to varyas the tape 120 moves through the cartridge 100.

These variations are pronounced in the outer rollers 148, 152 of theback set of rollers 140. If the two rollers 148, 152 had exactly equalrotational drag, the variations in drag caused by the inversely-varyingwrap angles would cancel each other out. In practice, however, thechanges in drag caused by the varying wrap angle can be substantial.

The wrap angle of the belt 136 relative to roller 150 of the back set ofrollers, in contrast, 140 is relatively constant. Therefore, the sideload from the belt 136 and drag provided by the roller 150 are alsorelatively constant. The drag exhibited by belt roller 150 issubstantially constant and greater than the drag exhibited by each ofthe other belt rollers 142, 144, 146, 148, 152 in the cartridge 100.Accordingly, the large drag component produced by the belt roller 150outweighs the smaller varying drag components introduced by the otherbelt rollers, and the total drag in the cartridge tends to be moreconstant over the length of tape moved between tape packs 110, 112.Thus, variations in the TDF and tape tension bow-tie profiles remainsmall as the tape 120 moves through the cartridge 100.

In alternative embodiments of the present invention, each of the rollersets 138, 140 may have fewer, or more, than three rollers. For example,certain configurations of the tape cartridge may not require rollers 148and 152 to guide the belt 136 away from the tape packs 110, 112.Instead, they may be replaced by a floating roller, as described in U.S.Pat. No. 4,209,144, to provide additional drag. Similarly, it may bedesirable to induce a total drag greater than the drag which can beproduced using only a single roller 150. In such situations, therotational drag imparted by other rollers, such as rollers 148 and 152,can also be increased in order to increase the total drag in thecartridge 100.

FIG. 2A illustrates a bottom view of the tape cartridge 100 embodimentillustrated in FIG. 1, and illustrates a “lockout” feature preventingthe tape cartridge 100 from being fully inserted into an incompatibletape drive. The baseplate 103 forms the bottom of the cartridge 100 andthe housing 210 forms the sides 102, 104, 106, 108 and top 205(overhanging portions of which are visible in FIG. 2A) of the cartridge100. The sides of the cartridge are substantially perpendicular to theplane of the baseplate 103 and, except near the front face 102 of thecartridge 100, the sides preferably extend only slightly beyond thebaseplate 103. The housing 104 forming the top 205 of the cartridge ispreferably parallel to the plane of the baseplate 103.

Near the front face 102 of the cartridge 100, the top 205 of the housing210 extends to the same dimensions as the baseplate 103. The portions ofthe housing forming the sides 106, 108 of the cartridge 100 are relievedrelative to the baseplate 103 and the top 205 of the housing, therebydefining a channel 211 on each side of the cartridge 100 for receiving arail 168, 170 of the tape drive. The baseplate preferably 103 has anotch 212 on each side 106, 108 of the cartridge 100 positioned toencounter a locking device in the tape drive when the cartridge 100 isfully inserted therein. The top 205 of the housing does not have acorresponding notch 212 and therefore forms a shoulder portion 213 abovethe notch 212. At the back of the notch 212, the top 205 of the housingextends outward from each side 106, 108 of the cartridge 100 to form anadditional overhanging shoulder portion 214, giving the top 205 of thehousing the wider dimension W′ relative to the width W of the front face102. Also, rearwardly of the notch 212, the housing 210 forming thesides 106, 108 of the cartridge 100 becomes substantially flush with thebaseplate 103, thereby eliminating the defined channels 211. 220Beginning at a point preferably approximately 0.8 inches from the frontface 102, the baseplate 103 and side portions 216 of the housing 210extend laterally in a tapered or curved manner for approximately 0.6inches to the wider dimension W′. As the baseplate 103 and side portions216 extend laterally, the extents of the overhanging shoulder portions214 are correspondingly diminished until the sides of the housing 210are substantially flush with the top 205 of the housing and thebaseplate 103.

In industry-standard conventional tape cartridges, the channels definedin the sides of the cartridge typically extend for almost 2.0 inchesbeyond the front face. Accordingly, when the conventional cartridge isinserted into a tape drive accepting conventional compatible tapecartridges, the rails in the tape drive extend through the definedchannels until the locking device in the tape drive engages the notchesin the baseplate and, in combination with the rails, holds the cartridgein position.

When a tape cartridge 100 according to the embodiment illustrated inFIG. 2 is inserted into an incompatible tape drive, the rails 168, 170in the tape drive encounter the tapered or curved portions 216 of thehousing and prevent the cartridge 100 from being fully inserted into thetape drive, thereby also preventing the locking device from engaging thenotches 212 in the baseplate 103, and preventing roller 146 fromengaging the drive capstan, and precluding the read/write head fromcontacting the tape 120 through the access port 134. In addition, theoverhanging shoulder portions 214 of the top 205 of the housing havingthe wider dimension W′ may encounter a front face of the tape drive andprevent further insertion of the cartridge 100 therein. Accordingly, thecartridge housing serves as a “lockout” device by preventing thecartridge 100 from being inserted into a non-compatible tape drive thatis designed to accept a different type of cartridge. Shoulders in thetop edges of the cover interfere with the tabs in the front bezel of anindustry standard drive. Additionally, stops in the side walls of thecover will prevent penetration of the rails of an industry standarddrive into the cartridge sufficient to engage the drive roller. Aperture215 in the baseplate 103 facilitates optical sensing therethrough of endportions of tape 120 in accordance with conventional industry standards.

FIG. 2B illustrates a top view of the tape cartridge 100 embodimentillustrated in FIG. 1 and illustrates the media access door 160 andwrite protect lock according to a preferred embodiment of the presentinvention. A partially open media access door 160 is shown in brokenlines.

The write protect lock is preferably in a substantially triangularrecessed portion 223 of the top 205 of the cartridge 100 positionedadjacent to the front left comer. The write protect lock preferablycomprises an arm 224 pivotally mounted about a pivot pin 226 insertedinto the top 205 of the cartridge and positioned adjacent to theback-most vertex of the recessed area 223. In one embodiment,indentations in the housing 104 restrain the arm 224 against either theleft or right side of the recessed portion 223 of the housing, but allowthe arm 224 to be moved with slight effort to the other side of therecessed portion. When the cartridge 100 is fully inserted into the tapedrive, sensors within the tape drive sense the position of the arm 224and determine whether to allow writing to the tape 120 in accordancewith conventional standards.

FIG. 2C illustrates a side view of the right side 108 of the tapecartridge 100 embodiment illustrated in FIG. 1. FIG. 2C more clearlyillustrates the channel 211 formed by the recessed side 208 of thehousing 210. Also shown is the end 164 of the media access door 160 onthe opposite side of the pivot pin 162 from the main body of the doorwhich serves as a pivoted actuator for opening the door 160 as the tapecartridge is inserted into a compatible tape drive.

FIG. 3 is a perspective view of a tape cartridge 300 according toanother embodiment of the present invention showing the baseplate 303and associated components. The front 302 of the baseplate 303 preferablyhas an industry-standard width of 3.188 inches and the housingpreferably has cartridge-drive interface openings in accordance withANSI specification X.3.249-1995. The back of the baseplate 303 isarcuate and also has a width of about 3.188 inches. Accordingly, thesides of the baseplate 306, 308 are parallel to each other andperpendicular to and flush with the front 302 and back 304. The lengthof the baseplate 303 is preferably approximately 5.0 inches, as measuredalong the center line 318. Of course, other industry-standard dimensionsmay be used to configure a cartridge for operational engagement with acompatible tape drive.

The cartridge is assembled on the baseplate 303 to include within thehousing front and back tape packs 310, 312, each comprising a rotatablymounted hub 314, 316. These hubs 314, 316 are preferably located alongand slightly askew a center line 318 extending lengthwise through thecartridge 300 and perpendicular to the front face 302. The front hub 314is slightly to the left of the center line 318 and the back hub 316 isslightly to the right of the center line 318. The hubs 314, 316preferably have diameters of about 0.6 inches. In addition, upper andlower flanges 315, 317, 319, 321 (flange 321 is hidden beneath the fronttape pack 110) are preferably respectively ultrasonically welded to andintegrally molded with the tops and bottoms of the hubs 314, 316 and arepositioned to guide the tape 320 onto the hubs 314, 316. Alternatively,the upper flanges 315, 317 may be chemically bonded to the hubs 314,316. Each flange has a preferred diameter of approximately 0.8 inchesand prevents the tape 320 in the portions of the tape packs 310, 312encountering the flanges from vertically shifting. In a preferredembodiment of the tape cartridge of FIG. 3, a spring 362, 364 is biasedagainst the top flange 315, 317 of each hub 114, 116 and flexed upwardat its ends to encounter the underside of the top of the cartridgehousing (not shown). The biases of the springs 362, 367 provide downwardforce on each hub 314, 316, which keeps the hubs 314, 316 against thebaseplate 303.

The magnetic recording tape 320 passes along a tape path from the frontpack 310, over a set of guides 322, 326, 328 and a pin 324 to the backpack 312. A preferred embodiment of the present invention hasapproximately 1200 feet of 8 millimeter-wide tape. FIG. 3 illustratestwo conditions of the tape 320 substantially fully wound about one ofthe hubs 314, 316. The figure illustrates the tape 320 by a solid line330 when substantially all of the tape 320 is wound upon the front hub314. As illustrated by solid line 330, the diameter of the front tapepack 310 is maximum and the diameter of the back tape pack 312 isminimum (at substantially the hub diameter) in that condition. Whensubstantially all of the tape 320 is transported to the back tape pack312, the diameter of the back tape pack 312 is maximum and the diameterof the front tape pack 310 is minimum (at substantially the hubdiameter). This condition is illustrated by broken line 332. In apreferred embodiment of the present invention, the maximum diameter of atape pack is approximately 2.1 inches, although this diameter may varyas a function of the hub diameter and tape length selected for assemblywithin the cartridge 300. Accordingly, the ratio of maximum packdiameter to minimum pack diameter is approximately 4:1.

The drive belt 334 drives the tape packs 310, 312 via movement along apath formed by front and back sets of belt rollers 336, 338 and the tapepacks 310, 312. The drive belt 334 wraps about an arcuate portion of thefront tape pack 310 from a point adjacent to roller 340 to a pointadjacent to roller 344, and about an arcuate portion of the back tapepack 312 from a point adjacent to roller 346 to a point adjacent toroller 342.

Roller 340 within the front set of rollers 336 also serves as the driveroller and includes an upper flange having a diameter of about 0.486inches that is positioned to contact a capstan when the tape cartridge300 is inserted into a compatible tape drive. When so inserted, themedia access door 350 pivoted on pin 352 is pivoted open via the leverarm 354 engaging a side surface 360 of a compatible tape drive, and aread/write head enters the space of access port 348 defined in thecartridge front 302 to make interface contact with the tape 320. At thesame time, the flanged portion of the drive roller 340 contacts thecapstan. When the capstan rotates, the rotation is imparted to the driveroller 340 and to the drive belt 334 which is wrapped about a portion ofthe drive roller 340 below the flange having a narrowed diameter. Thedrive belt 346 engages the outer wraps of tape wound on the tape packs310, 312 and causes the tape packs 310, 312 to rotate. Depending uponthe direction of rotation of the drive roller 340, one tape pack servesas a supply pack and the other pack serves as the take-up pack.

The media access door 350 is preferably pivotally mounted about a pin352 positioned adjacent to the right front comer of the cartridge 300and preferably extends from the left side of the access port 348 towardthe right side of the front face 302 of the cartridge. The media accessdoor 350 is biased closed by a spring that is wrapped around the pin352. The closed media access door 350 covers and protects the portion ofthe tape 320 passing through the media access space 348.

FIG. 3 illustrates a partial view of the left 358 and right 356 rails ofa tape drive for accepting a cartridge 300 according to the embodimentof FIG. 3. When the cartridge 300 is inserted into the tape drive, anextended portion 360 on the right rail 356 of the tape drive engages theend 354 of the media access door 350 on the opposite side of the pivotpin 350 from the main body of the door and pivots the door open aboutthe pivot pin 350, thereby allowing access to the components of the tapecartridge 300 behind the door.

FIG. 4A illustrates a bottom view of the tape cartridge 300 embodimentillustrated in FIG. 3. The baseplate 303 forms the bottom of thecartridge 300 and the housing 410 forms the sides 302, 304, 306, 308 andtop of the cartridge 300. The sides of the cartridge are substantiallyperpendicular to the plane of the baseplate 303 and the top of thecartridge is substantially parallel to the plane of the baseplate 303.

Near the front face 302 of the cartridge 300, the housing 410 formingthe top of the cartridge 300 extends to the same dimensions as thebaseplate 303 and the portions of the housing forming the sides 306, 308of the cartridge 300 are relieved relative to the baseplate 303 and thetop of the housing 410, thereby defining a channel 411 on each side ofthe cartridge 300. The baseplate 303 has a notch 412 on each side 306,308 of the cartridge 300 positioned to encounter a locking device in acompatible tape drive when the cartridge 300 is fully inserted therein.The top of the housing does not have a corresponding notch 412 andtherefore forms a shoulder portion 413 above the notch 412. Rearwardlyof the notch 412, the top of the housing extends outward from each side306, 308 of the cartridge 300 to form additional overhanging shoulderportions 414 having a wider dimension W′ relative to the width W of thefront face 302 and the baseplate 303. Also rearwardly of the notch 312,the housing 410 forming the sides 306, 308 of the cartridge 300 becomessubstantially flush with the baseplate 303, thereby eliminating thedefined channels 411.

Beginning at a point preferably approximately 0.75 inches from the frontface 302, the side portions 416 of the housing 410 extend laterally in atapered or curved manner for approximately 0.6 inches to the widerdimension W′. As the side portions 416 extend laterally, the extent ofthe overhanging shoulder portions 414 beyond the side portions 416 iscorrespondingly diminished until the sides of the housing 410 extend tothe same width W′ as the top of the housing, which is approximately 0.25inches beyond the baseplate 303. As shown in FIG. 4A, the housing 410wraps around the baseplate 303. The back of the housing 304 issubstantially parallel to the front face 302 and, since the back of thebaseplate 303 is arcuate, the extension of the housing 410 beyond thebaseplate 303 at the back of the cartridge 300 is correspondinglyreduced in order to maintain this parallelism.

When a tape cartridge 300 according to the embodiment illustrated inFIG. 3 and having the housing illustrated in FIG. 4A is inserted into atape drive that is adapted to receive a conventional prior artcartridge, the rails 356, 358 in the tape drive encounter the block 412of the housing and prevent the cartridge 300 from being fully insertedtherein. In some tape drive embodiments, the overhanging shoulderportions 414 of the housing encounter the front face of the tape driveand prevent the cartridge 300 from being inserted therein. Accordingly,the cartridge housing according to the present invention prevents thecartridge 300 from being inserted into a tape drive designed to accept adifferent type of cartridge.

FIG. 4B illustrates a top view of the tape cartridge 300 embodimentillustrated in FIG. 3 and illustrates the top 430 of the housing, themedia access door 350, and the write protect lock 424 according to apreferred embodiment of the present invention. A partially open mediaaccess door 350 is shown in dotted lines. Like in the embodimentillustrated in FIG. 2B, the write protect lock 424 is preferably in asubstantially triangular recessed portion of the top of the cartridge300 positioned adjacent to the front left corner for operation in themanner as previously described herein. In addition, a gap 422 defined inthe top 430 and front 302 of the housing 410 exposes the flanged portionof the drive roller 340.

FIG. 4C illustrates a side view of the right side 308 of the tapecartridge 300 embodiment illustrated in FIG. 3. FIG. 4C more clearlyillustrates the channel 411 formed in the side of the cartridge by therecessed side 308 of the housing 41 0, and the block 412 which preventsinsertion into a standard drive. Also shown is the end 354 of the mediaaccess door 350 on the opposite side of the pivot pin 352 from the mainbody of the door which acts as a pivot arm for opening access door 350in a manner as previously described herein.

Therefore, the improved tape cartridge according to the presentinvention allows use of a longer length of tape while minimizingundesirable effects, including increased variation in bow-tie tensionand TDF profiles typically encountered when using a longer tape. Thelonger and wider cartridge housing allows more tape and larger hubs thanpossible in industry-standard tape cartridges. Also, flanges on the hubsprevent the tape pack from shifting. Moreover, selected rollers minimizevariations in tape tension and drag over an entire length of tape thatis attributable to changes in the diameters of the tape packs. Inaddition, the shorter-length channels defined in the sides of thecartridge prevent the cartridge from being inserted into anon-compatible tape drive, and the write protect lock allows easychanging of the write protect status.

What is claimed is:
 1. A tape cartridge comprising: a substantiallyrigid baseplate; a housing coupled to the baseplate and comprising: aplanar front face substantially flush with the baseplate and with amedia access opening for interfacing with a tape cartridge drive; aplanar back face opposite the front face; left and right side wallsextending from the front face to the back face having recessed portionsrespectively defining channels in the left and right sides of the tapecartridge, the defined channels beginning at the front face and endingless than approximately 0.8 inches from the front face; and a topsubstantially parallel to the baseplate, extending from the front faceto the back face, and having shoulder portions extending laterallybeyond the left and right side walls positioned less than approximately0.8 inches from the front face.
 2. A tape cartridge comprising: asubstantially rigid baseplate having left and right sides; a housingcoupled to the baseplate and comprising: a planar front facesubstantially flush with the baseplate and with a media access openingfor interfacing with a tape cartridge drive; a planar back face oppositethe front face; left and right side walls extending from the front faceto the back face and having portions tapering outward, the outwardtapered portions of the left and right side walls ending approximately1.4 inches from the front face; and a planar top parallel to a plane ofthe baseplate and having left and right shoulder portions extendinglaterally relative to the respective left and right sides of thecartridge, the left and right shoulder portions located closer to thefront face than the beginning of the tapered portions of the left andright side walls.